Piezoelectric transducers are used in a speaker for converting electrical wave into a sound wave. Typically, a clamping device is used to put pressure directly onto the piezoelectric ceramic or crystal used as the transducer element, as illustrated in the U.S. Pat. No. 2,123,236. Change in the clamping pressure causes a shift in the point of contact of the crystal with the supporting element of the crystal and the shift causes a change in the frequency of the vibration provided by the transducer.
The variation in the bending of the electrode made of the metal plate holding the transducer element such as piezoelectric ceramic or crystal also causes a change in the frequency. The prior art piezoelectric transducer apparatus and, in particular, the crystal holder of the transducer apparatus are found to be deficient in that the pressure applied directly to the transducer element such as the piezoelectric ceramic or crystal does not permit the adjustment of the overall transducer apparatus to the maximum alertness possible.